Adjustable resistance



May 1, 1928.

'- A. A'. KENT ADJUSTABLE RESISTANCE Filed Feb. 15, 1923 I N VEN TOR.

2Z2 ATTORNEY.

Patented May 1, 1928.

ARTHUR Amwarnn KENT, or nanmoan, PENNSYLVANIA.

ADJUSTABLE RESISTANCE.

Application filed February 15, 1923. Serial No. 619,136.

My invention relates to adjustable resistances in general and more particularly to adjustable resistances utilizable as poten-.

ture, arrangement and combination of the character hereinafter described and claimed.

F or an illustration of one of the various forms my invention may take, reference is to be had to the accompanying drawing, in which:

Fig. 1 is a top plan view of structure embodying my invention.

Fig. 2 is a vertical sectional View taken on the line 22 of Fig. 1.

Fig. 3 is a bottom plan view of the structure shown in Figs. 1 and 2.

Fig. 4 is a fragmentary vertical sectional view on the line 44 of Fig. 1.

Fig. 5 is a fragmentary view of the resistance element which I employ.

Referring to Figs. 1 and 2, 5 is a cover or casing, of molded insulating material, as condensite or bakelite, by which the various parts of the apparatus are supported and is provided with ears 6 by means of which it may be fastened to a panel board or base (not shown).

Wound about a strip 7 of insulating ma--.

terial, as bakelized canvas, fibre or the like, is the resistance wire or conductor 8, preferably having low ten'lperature coefficient. The member 7, with the wire 8 wound thereon, is bent to conform with and inserted edgewise into an annular recess 9 between the raised ridge or rib 9* and the wall 5, for holding the resistance element in proper position within the casing.

The ends of the resistance wire8 and its core 7 are secured to the box by screws 11 and 12, that extend through holes 7 of the core 7 and holes in the wall 5 of the box 5 and are provided with nuts 13 and 14, respectively, the ends of the resistance unit being held between metallic clamping members 15, 16 and the wall 5 of the box 5. The clamps 15 and 16 are bent laterally at 15 and 16 to form lugs for confinin the resistance unit. At each end of the unit the end turns of the wire 8 are clamped beneath the members 15-and 16 and make electrical connection therewith.

A binder, such as collodion, may be ap plied to the side of the resistance unit which lies against the wall of the cover 5, to assist 1n holding the unit more rigidly in position within the cover or casing 5.

The outer ends of the screws 11 and 12 serve as binding posts having the binding nuts 17 and 18, respectively, that serve to bind conductors (not shown) between washers 21 and 22and the nuts 13 and 14, respectively.

A shaft 23 extends through the cover 5 and is providedupon its outer end with a knob 24 and a pointer 25. Upon its inner end the shaft 23 is provided with an arm 26 which is held in placeupon the shaft 23 by a set screw 27. The arm 26 is provided with Y a recess in which a spring 28 and a brush member 29 are disposed. The spring 28 serves to hold the brush in engagement with the conductor 8 on the flat side of the resistance unit as the arm 26 is rotated by knob A yielding metallic conductor 31, provided with bifurcations 32 (Fig. 3) is disposed radially of the box 5, and its inner end engages in the circumferential notch 23 in shaft 23. The other end of the member 31 is held against the wall 5 by a binding post 33 which is in turn held in position by means of a nut 34. A binding nut 35 engages the. outer end of the screw 33 and serves-to hold a conductor (not shown) between washer 36 and the nut 34.

By turning the knob 24, the brush 29 moves to different positions along the flat side of the resistance unit and different amounts of resistance are placed in circuit between the terminals 17 and 18 and the terminal 35, thus making it possible to pro cure a desired difference in potential between theterminals 35 and either of the terminals 17 and18.

The device may also be employed as a rheostat to vary the strength of current passing through the terminal 35 and either of the terminals 17 or 18.

From the foregoing descriptionit will be observed that the brush 29 moves along the inner wide or flat surface of the resistance member and has presented thereto a wide contacting surface, thus reducing wear of the resistance conductor and securing an effective electrical connection between the brush and the resistance conductor.

The pointer 25 is rigidly secured to the 1. Aresistance device comprising a casing having side and end walls, aresistance element disposed adjacent to the side wall, a clamping member engaging the exposed side of said element and provided with a flange overlying the outer edge of said element, and means for securing said clamping member in position. I

2. A resistance device comprising acasing having side and end walls, a resistance element disposed against the side wall. clamping members engaging the exposed side of said element at each end thereof and provided with flanges overlying the outer edge of said element, and 'means extending through said side wall for holding said clamping members in tight engagement with said element.

3. A resistance device comprising a casing having side and end walls, a rib onthe end wall located adjacent to the side wall to form a recess, a flat resistance element having one edge extending into said recess, a clamping member engaging the exposed side of said element above said recess and provided with a flange overlying the outer edge of said element, and means for securing said clamping member in position.

4. A resistance device comprising a casing A having side and end walls, a shaft extending through said end'wall and operable from the exterior of said casing, a movable contact member mounted upon said shaft within said casing and 'extendlng radially thereof, and a resistance device inthe form of a circular strip disposed within said casing in position to be engaged by said movable contact member, members clamping the ends of said strip to said side wall, said shaft having a circumferential notch, and a conducting spring secured to said side wall and engaging in said notch to effect electrical connection with said movable contact member and to bias said shaft longitudinally.

I 5. A- resistance device comprising a wall, a resistance element composed of wire transversely wound upon a strip of material and disposed against said wall, a clamping member engaging the end turns of said wire on the exposed side of said element, and means for holding said clamping member tightly in engagement with said element.

- 6. A resistance device compri's'inga casing,

a resistance element mounted within the casing, a shaft extending through a wall of the casing and provided with a circumferential notch, a contact member mounted upon the inner end of the shaft in position to en age said resistance element, and a conductor aving one end secured to an inner wall of the casing and its other end extending into said notch to make electrical connectiorrwith said ,shaft. f

7. A resistance device comprising a casing, a resistance element mounted within the easing, a shaft extending through a wall of the casing and provided with a circumferential notch, a contact memberv mounted upon the inner end of the shaft in position to engage said resistance element, and a conductor having one end secured to an inner wall of the casing and having its other end extending into said notch and bifurcated to partially embrace said shaft, the said conductor being biased axially of the shaft to yieldingly engage one wall of said notch.

8. A resistance device comprising a casing, a resistance element mounted within the easing, a shaft extending through a wall of the casing and provided with a circumferential notch, a contact member" mounted upon the inner end of the shaft in position to en age said resistance element, and a conductor aving one end secured to an inner wall of the casing and having its otherv end extending into said notch and bifurcated to partially embrace said shaft, the said conductor being of yielding-material and normally engaging one wall of said notch.

' 9. A resistance device comprising a resistance conductor wound transversely around a fiat strip, a casing adjacent an inner wall of which said strip isdisposed, a clamping member engaging and electrically connecting with said reslstance conductonand terminal structure extending through a wall of said casing and connecting with said clamping,

member.

10. A resistance device comprising a resistance conductor wound transversely around a fiat strip, a casing adjacent an inner wall of which said strip is disposed, a clamping member engaging and electrically connecting with said resistance conductor, binding post structure extending through a Wall of said casing and connecting with said clamping member, and a contact member movable along said resistance conductor between the edges of said strip, said clamping member serving as a stop for said contact member. v

11. A potentiometer comprising a casing having end and side walls, a resistance element comprising a flat strip and a resistance wire wound transversely thereof, binding screws extending throu h said side wall electrically connecting wit and exerting pres sure upon the inner exposed face of said strip thereby clamping said strip to said side wall, a shaft extending through said end wall and operable from the exterior of said 63S? ing, a movable contact carried by said shait and engaging said inner exposed face of said resistance element, a third bin-ding screw extending through said side wall between the ends of said resistance element, and means held by and electrically connecting with said third screw and electrically connecting with 10 said contact.

In testimony whereof I have hcreuntoaffixed my signature this 13th day of F ebruary, 1923.

ARTHUR ATWATER KENT. 

